1. Field of the Invention
The present invention relates to a zoom camera including a zoom photographing optical system having a predetermined zoom range and which is retractable to a position rearward of the predetermined zoom range. A zoom finder is also provided which is driven by a drive source and which drives the photographing optical system to vary the field of view of the finder in accordance with the focal length of the photographing optical system.
2. Description of Related Art
In a known zoom camera, the drive source (motive power) of a zoom motor is transmitted to a group of lenses of the zoom photographing optical system, not only to carry out the zooming operation but also to drive a group of movable variable power lenses of the zoom finder through a planar cam. The planar cam is made of a flat plate which is provided with a guide groove so that when the planar cam is moved in the left or right directions by the zoom motor, the movable variable power lens group of the zoom finder is moved in the optical axis direction through the guide groove. As a result, the position of the movable variable power lens group relative to the stationary lens group changes so that the field of view of the finder varies in accordance with the focal length of the photographing optical system.
It should be recalled that the planar cam is driven by the same zoom motor (drive source) that drives the zoom Photographing optical system and, accordingly, the zoom finder is inevitably driven when the lens barrel is retracted from within a zoom range in which the zooming can be affected by the photographing optical system to a position behind the zoom range. In other words, the field of view is changed beyond the wide angle extremity of the zoom range, in the retracted position, in which there is no need for observation through the finder. To avoid this, it is necessary to provide a linear guide groove on the planar cam to prevent the movable variable power lens group from moving beyond the zoom range.
To this end, the planar cam has a linear cam groove which does not contribute to the zooming, in addition to the guide groove along which the movable variable power lens group is moved during the zooming. The linear cam groove increases the lateral length and the displacement of the planar cam, resulting in an obstacle to the goal of a small and compact camera.